Cable tray is used by industry to support electrical cable. A length or section of cable tray comprises a pair of side rails connected by cable-supporting rungs extending between the rails at intervals along the tray. The side rails are typically made from sheet metal of a particular gauge (i.e., thickness). Typically, supports, such as trapeze supports, are installed at regular intervals of the cable tray run.
Cable trays are rated according to their load-bearing capacities. For example, the International Electrotechnical Commission (IEC) has a standard IEC 61537 to determine the load-bearing capacity of a cable tray. In general, the rated load-bearing capacity of a cable tray is the load on the cable tray that deflects the cable tray 1/100th of the span length using one of a number of predefined test methods, such as type II test. For example, using a cable tray having a span of 6 m during the type II test, the load on the cable tray that causes the cable tray to deflect 60 mm ( 1/100th of 6 m) is the rated load-bearing capacity of that specific tray.
One way to increase load-bearing capacity for particular cable tray is to increase the thickness or gauge of the rails. However, this approach increases both the weight and the cost of the cable tray.